Wireless communication device, wireless communication method, and computer program

ABSTRACT

An own-group storage area in which beacon information concerning a group of the own device is stored and an other-groups storage area in which beacon information concerning other groups different from the group of the own device is stored are allocated to a memory area of a wireless communication device in a network. The wireless communication device includes storage means for storing the beacon information concerning the other groups in the own-group storage area and the other-groups storage area in the same structure as that of the beacon information concerning the group of the own device.

CROSS REFERENCES TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 11/417,124, filed May 4,2006 now U.S. Pat. No. 7,751,840 and currently allowed. Application Ser.No. 11/417,124 claims priority to Japanese Patent Application JP2005-135224 filed in the Japanese Patent Office on May 06, 2005. All ofthe applications are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a communication device capable ofwireless communication.

2. Description of the Related Art

Communication systems capable of network connection by wirelesscommunication between multiple communication devices, such as computerdevices having communication functions, have become popular asinformation processing technologies have become more advanced.

Such communication systems are specified in, for example, Institute ofElectrical and Electronic Engineers (IEEE) 802.11 (for example, refer toInternational Standard ISO/IEC 8802-11:1999(E) ANSI/IEEE Std 802.11,1999 Edition, Part II: Wireless LAN Medium Access Control (MAC) andPhysical Layer (PHY) Specifications) and IEEE 802.15.3.

“Ad hoc networks” over which communication devices directly andasynchronously perform the wireless communication have been developed asone type of networks utilizing the above communication systems. The adhoc communication systems have no control station and are suitable for,for example, home networks including household electric appliances (forexample, refer to Japanese Unexamined Patent Application Publication No.2000-165930).

In order to detect wireless communication devices around the own deviceand to know the behaviors of the wireless communication devices, such anad hoc networks employs a method of defining a time area in apredetermined superframe as a beacon period between the wirelesscommunication devices belonging to the network group of the own deviceand sharing the timings in the beacon period between the wirelesscommunication devices belonging to the network group to ensureconnection between the wireless communication devices belonging to thenetwork group.

In the above ad hoc network, it is important to set the timings in thebeacon period defined between the wireless communication devices in thenetwork group of the own device such that the beacon transmissionpositions (beacon slots) of the own device do not coincide with thebeacon transmission positions of other wireless communication devices.

Since the beacons communicated between the wireless communicationdevices in the network group of the own device are concentrated on onetime in the beacon period, there is a need to manage the beacon periodsto determine all the wireless communication devices in the network.

SUMMARY OF THE INVENTION

Although it is necessary to manage the beacons of wireless communicationdevices that belong to network groups different from the network groupof the own device and that enter the network, along the beacon periodsof the wireless communication devices in the network group of the owndevice, in the configuration of the above ad hoc network, it isdifficult to manage such beacons because management means forcollectively managing such beacons does not exist.

Specifically, when multiple network groups enter the network, it isnecessary to collectively manage the beacon periods of the wirelesscommunication devices in the network group of own device and the beaconperiods of the wireless communication devices in other network groupsand to store the beacon information concerning the wirelesscommunication devices in the network group of the own device and thebeacon information concerning the wireless communication devices in thenetwork groups different from the network group of the own device in thememory areas of the respective wireless communication devices. However,such storage means does not disadvantageously exit.

It is desirable to provide a new and improved wireless communicationdevice, wireless communication method, and computer program, which arecapable of storing beacon information concerning the beacon period ofthe own device and beacon information concerning beacon periodsdifferent from that of the own device.

According to an embodiment of the present invention, there is provided awireless communication device in a network. An own-group storage area inwhich beacon information concerning a group of the own device is storedand an other-groups storage area in which beacon information concerningother groups different from the group of the own device is stored areallocated to a memory area of the own device. The wireless communicationdevice includes storage means for storing the beacon informationconcerning the other groups in the own-group storage area and theother-groups storage area in the same structure as that of the beaconinformation concerning the group of the own device. With this structure,the wireless communication device can collectively manage the beaconinformation concerning the group of the own device and the beaconinformation concerning other groups different from the group of the owndevice to appropriately communicate with destination communicationdevices.

The other-groups storage area may be allocated to a memory area behindthe memory area of the own-group storage area.

When the beacon information is stored, the storage means may determine amaximum number of counted communication devices in the network and maysequentially store the beacon information of a number corresponding tothe maximum number of counted communication devices, concerning theother groups, from the end of the own-group storage area.

The wireless communication device may include management means forallocating device-specific information unique to each wirelesscommunication device around the own device to manage the wirelesscommunication devices, which are destination devices, by using thedevice-specific information.

It is possible that the device-specific information does not depend on abeacon transmission position and a device address and has a minimumlength.

According to another embodiment of the present invention, a wirelesscommunication device in a network includes a storage unit configured tostore beacon information resulting from initial scanning in the samestructure as that of normal beacon information yielded in operation ofthe network in a memory area of the own device. With this structure,since the wireless communication device manages the beacon informationin the same structure even in the initial scanning, it is possible todiscriminate the beacon information concerning the group of the owndevice from the beacon information concerning other groups differentfrom the group of the own device after several superframe periods toindividually and easily mange the beacon information.

According to yet another embodiment of the present invention, a wirelesscommunication device in a network includes scanning setup means forperforming scanning at arbitrary timings, in addition to initialscanning; detecting means for detecting a wireless communication devicehaving a different beacon period; and memory means for storing beaconinformation concerning the wireless communication device having thedifferent beacon period in a memory area.

The wireless communication device may further include calculating meansfor calculating a timing at which a reserved communication area is setfrom at least the beacon information stored in the memory means;comparing means for comparing the timing of the calculated reservedcommunication area with the timing of the reserved communication area ofthe own device; and setting means for setting the communication areassuch that the timings of the communication areas do not coincide witheach other, in accordance with the comparison result.

The wireless communication device may further include storage means forstoring the beacon information in other beacon periods in the samestructure as that of the beacon information concerning a wirelesscommunication device having the beacon period of the own device, storedin the memory area in the memory means.

The beacon information resulting from the initial scanning may be storedin the same structure as that of the beacon information concerning thewireless communication device having the beacon period of the own devicein the memory area in the memory means.

The wireless communication device may further include setting means, forsetting a maximum number of counted communication devices in thenetwork. The storage means may sequentially store the beacon informationconcerning the wireless communication device having a beacon perioddifferent from the beacon period of the own device from the end of thearea where the beacon information in the beacon period of the own deviceis stored.

The wireless communication device may further include allocating meansfor allocating a device identifier specific to each wirelesscommunication device around the own device; and managing means formanaging the wireless communication devices around the own device, whichare destination devices, by using the device identifier.

According to still another embodiment of the present invention, awireless communication method for a wireless communication device in anetwork includes the steps of performing scanning at arbitrary timings,in addition to initial scanning; detecting a wireless communicationdevice having a different beacon period; and storing beacon informationconcerning the wireless communication device having the different beaconperiod in a memory area. According to still yet another embodiment ofthe present invention, a computer-executable program causing a computerto function as a wireless communication device in a network includesinstructions for performing scanning at arbitrary timings, in additionto initial scanning; instructions for detecting a wireless communicationdevice having a different beacon period; and instructions for storingbeacon information concerning the wireless communication device havingthe different beacon period in a memory area.

As described above, according to the present invention, both the area inwhich the beacon information concerning the group of the own device isstored and the area in which the beacon information concerning othergroups is stored are provided to manage the multiple network groupsaround the own device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing an example of theconfiguration of a wireless ad hoc network by autonomous distributedcontrol, according to the embodiment of the present invention;

FIG. 2 is a diagram schematically showing the structure of a superframeaccording to an embodiment of the present invention;

FIG. 3 is a diagram schematically showing use of beacon slots accordingto an embodiment of the present invention;

FIG. 4 is a diagram schematically showing the structure of a beaconframe according to an embodiment of the present invention;

FIG. 5 is a diagram schematically showing an example of the structure ofa memory area in a memory in which beacon information concerning thenetwork group of the own device is stored, according to an embodiment ofthe present invention;

FIG. 6 is a diagram schematically showing an example of the structure ofa memory area in the memory, in which beacon information concerningother network groups is stored, according to an embodiment of thepresent invention;

FIG. 7 is a diagram schematically showing an example of the managementstructure of a communication device by using device-specificinformation, according to an embodiment of the present invention;

FIG. 8 is a block diagram schematically showing an example of thestructure of a wireless communication device according to an embodimentof the present invention;

FIG. 9 is a diagram schematically showing management of communicationdevices around the own device, according to an embodiment of the presentinvention;

FIG. 10 is a diagram showing an example of the structure in whichresults of beacon scanning in initial setup are stored, according to anembodiment of the present invention; and

FIG. 11 is a flowchart schematically showing an operation of thecommunication device, according to an embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described with reference tothe attached drawings. The same reference numerals are used in thefollowing description and the attached drawings to identify thecomponents having approximately the same functions and structures. Adescription of such components is not repeated herein.

FIG. 1 is a diagram schematically showing an example of theconfiguration of a wireless ad hoc network by autonomous distributedcontrol, according to an embodiment of the present invention.

Referring to FIG. 1, a communication device 101-1 is capable of wirelesscommunication with a communication device 101-2 located within the radiowave spectrum (denoted by a broken line) around the communication device101-1.

The communication device 101-2 is capable of the wireless communicationwith the communication device 101-1 and communication devices 101-3 and101-4, which are located within the radio wave spectrum (denoted by abroken line) around the communication device 101-2.

The communication device 101-3 is capable of the wireless communicationwith the communication device 101-2 and communication devices 101-7 and101-8, which are located within the radio wave spectrum (denoted by abroken line) around the communication device 101-3.

The communication device 101-4 is capable of the wireless communicationwith the communication device 101-2 and a communication device 101-5,which are located within the radio wave spectrum (denoted by a brokenline) around the communication device 101-4.

The communication device 101-5 is capable of the wireless communicationwith the communication devices 101-4, a communication device 101-6, andthe communication device 101-7, which are located within the radio wavespectrum (denoted by a broken line) around the communication device101-5.

The communication device 101-6 is capable of the wireless communicationwith the communication devices 101-5 and 101-7, which are located withinthe radio wave spectrum (denoted by a broken line) around thecommunication device 101-6.

The communication device 101-7 is capable of the wireless communicationwith the communication devices 101-3, 101-5, 101-6, and 101-8, which arelocated within the radio wave spectrum (denoted by a broken line) aroundthe communication device 101-7.

The communication device 101-8 is capable of the wireless communicationwith the communication devices 101-3 and 101-7 and a communicationdevice 101-9, which are located within the radio wave spectrum (denotedby a broken line) around the communication device 101-8.

The communication device 101-9 is capable of the wireless communicationwith the communication device 101-8 located within the radio wavespectrum (denoted by a broken line) around the communication device101-9.

The communication devices 101-1, 101-2, 101-3, and 101-4 form a firstnetwork group. The communication devices 101-1 to 101-4 are shown withfirst hatching.

The communication devices 101-5, 101-6, and 101-7 form a second networkgroup. The communication devices 101-5 to 101-7 are shown with secondhatching.

The communication devices 101-8 and 101-9 form another network groupdifferent from the first and second network groups. The communicationdevices 101-8 to 101-9 are shown with third hatching.

The communication device 101-4 in the first network group and thecommunication device 101-5 in the second network group receive beaconsignals from communication devices belonging to the network groupsdifferent from each other.

The communication device 101-3 in the first network group and thecommunication device 101-7 in the second network group also receivebeacon signals from communication devices belonging to the networkgroups different from each other.

The first network group and the second network group achieve thecoexistence by sharing one beacon period.

In other words, the first network group and the second network groupform one large network group.

The communication device 101-8, which belongs to a network groupdifferent from the first and second network groups, is located at aposition where the communication device 101-8 is capable ofcommunication with the communication devices 101-3 and 101-7.

Since the communication device 101-8 has a beacon period different fromthose of the first and second network groups, the communication device101-8 does not transmit beacons in the beacon period common to the firstand second network groups.

There are cases where the communication devices 101-1 to 101-9 aresimply and collectively referred to as a communication device 101 inthis specification. In such a case, the communication device 101corresponds to at least one of the communication devices 101-1 to 101-9.

FIG. 2 is a diagram schematically showing the structure of a superframeaccording to an embodiment of the present invention.

A superframe period over a predetermined time is defined in a mannershown in FIG. 2. The superframe period is divided into 256 media accessslots (MASS), such as “MAS0” to “MAS255”.

The superframe includes a beacon period serving as a management area anda data transmission area, as shown in FIG. 2.

The beacon period has beacon slots set therein at predeterminedintervals. Each communication device 101 uses its own beacon slot totransmit and receive beacons to and from the communication devices 101around the own device (the communication device 101 itself) in order toexchange parameters between the communication devices 101.

The length of the beacon period depends on the number of thecommunication devices 101 around the own device. That is, the number ofthe communication devices 101 determines a required length of the beaconperiod.

According to the embodiment of the present invention, the MASs from theMAS0 to the MAS3 are used as the beacon period, as shown in FIG. 2. Thebeacon period has a total of 12 beacon slots from a beacon slot 0 (BS0)to a beacon slot 11 (BS11).

FIG. 3 is a diagram schematically showing use of the beacon slots ineach communication device 101 according to an embodiment of the presentinvention.

Each communication device 101 in one network group indicates unusedbeacon slots to the communication devices 101 around the own device toshow the beacon slot selected by the own device. FIG. 3 also shows howto share a common beacon period between the communication devices 101around the own device, irrespective of the network group.

The communication device 101-1 in the first network group transmits itsown beacon in the beacon slot 6 (BS6).

The communication device 101-2 in the first network group transmits itsown beacon in the beacon slot 3 (BS3), and the communication device101-3 in the first network group transmits its own beacon in the beaconslot 7 (BS7).

The communication device 101-4 in the first network group transmits itsown beacon in the beacon slot 4 (BS4).

The communication device 101-5 in the second network group transmits itsown beacon in the beacon slot 2 (BS2), and the communication device101-6 in the second network group transmits its own beacon in the beaconslot 5 (BS5).

The communication device 101-7 in the second network group transmits itsown beacon in the beacon slot 1 (BS1).

Although the beacon slot 0 (BS0) and the beacon slot 8 (BS8) areprovided, if necessary, in preparation for new communication devices 101that enter other network groups different from the first and secondnetwork groups, the embodiment of the present invention is not limitedto this case.

As shown in FIG. 3, the communication device 101-8 belonging to anothernetwork group transmits its own beacon in the beacon slot 2 (BS2) in thebeacon period of the other network group, and the communication device109 transmits its own beacon in the beacon slot (BS1) in this beaconperiod.

Similarly, although the beacon slot (BS0) and the beacon slot 3 (BS3)are provided, if necessary, in preparation for new communication devices101 that enter the other network group, the embodiment of the presentinvention is not limited to this case.

FIG. 4 is a diagram schematically showing an example of the structure ofa beacon frame according to the embodiment of the present invention.

Since the beacon frame is transmitted from each communication device 101in the management area (beacon period) of the superframe, eachcommunication device 101 can receive all the beacons transmitted fromthe communication devices in the management area (beacon period) toexchange the parameters between the communication devices 101 around theown device.

As shown in FIG. 4, the beacon frame includes MAC header information 41,a header check sequence (HCS) 42, beacon payload information 43, and aframe check sequence (FCS) 44.

The MAC header information 41 includes frame control information 401, adestination address 402, a source address 403, sequence managementcontrol information 404, and access control information 405.

Information processing over a radio communication network iscollectively called “Access”. The information processing includesconnection between the communication devices 101, reference toinformation owned by another communication device 101 from thecommunication device 101, and storage, deletion, or modification ofinformation owned by another communication device 101 from thecommunication device 101.

The beacon payload information 43 includes a beacon parameter 406,beacon period occupancy 407, a capability 408 of the communicationdevice 101, transmission indication 409, an available MAS 410, and areserved MAS 411.

FIG. 5 is a diagram schematically showing an example of the structure ofa memory area in a memory (storage unit), in which beacon informationconcerning the network group of the own device is stored, according toan embodiment of the present invention.

The memory area in the memory, shown in FIG. 5, includes the beaconinformation concerning one or more network groups operating in thebeacon period of the own device.

Specifically, the beacon information concerning the first and secondnetwork groups, which have the same beacon period, is stored in thememory.

The beacon information that is received is stored in the memory forevery beacon slot position 501.

The memory area in the memory includes a device index 502, a beaconstatus 503, beacon slot information 504, the number of lost beacons 505,a device address 506, a device identifier 507, a beacon slot number(BSN) 508, control information 509, a received information element (IE)bitmap 510, a beacon period occupancy information element (BPOIE) 511,and capability 512 of each beacon slot position 501. The device index502 indicates information specific to the communication device. Thebeacon status 503 indicates whether the beacon information is receivedin the beacon slot. The beacon slot information 504 indicates the usageof the beacon slot in the beacon period. The number of lost beacons 505indicates a counted number of beacons that are temporarily lost.

The device address 506 described in a header in FIG. 5, and the deviceidentifier 507 being information concerning the MAC address, the BSN508, and the control information 509, which are described in a beaconparameter in FIG. 5, are arranged as common information concerning thereceived beacon.

Furthermore, the received IE bitmap 510 indicating which informationelement is included; the BPOIE 511 indicating the usage of the beaconperiod; and the capability 512, which is the information elementindicating the capability of the communication device 101, are arranged,if necessary, in an area (as IE parameters of the received beacon), inwhich parameters added as variable length information are stored. TheBPOIE 511 and the capability 512 show the content of the informationelement described in the received IE bitmap 510. However, the aboveinformation is only exemplified and other beacon parameter informationmay also be arranged.

The information concerning the communication device 101-3 (DEVID 3) isstored in the memory on the basis of the parameters, for example, in thestructure shown in FIG. 5. The received beacon information is stored inthe memory as the information in the beacon period of the own device.

As shown in FIG. 5, since the beacon slot 1 (BSN1) receives the beaconof the communication device 101-7 (DEVID 7), the beacon slot 1 (BSN1)has the parameters of the communication device 101-7 and DI=2 isassigned as the device index 502.

Since, although the beacon slot 2 (BSN2) does not receive the beacon, itis determined that the communication device 101-5 (DEVID 5) uses thebeacon slot 2 (BSN2) from the BPOIE indication from the communicationdevice 101-7, the parameters concerning the communication device 101-5are described in the beacon slot 2 (BSN2).

Since the beacon slot 3 (BSN3) receives the beacon of the communicationdevice 101-2 (DEVID 2), the beacon slot 3 (BSN3) has the parameters ofthe communication device 101-2 and DI=1 is assigned as the device index502.

Since, although the beacon slot 4 (BSN4) does not receive the beacon, itis determined that the communication device 101-4 (DEVID 4) uses thebeacon slot 4 (BSN5) from the BPOIE indication from the communicationdevice 101-2, the parameters concerning the communication device 101-4are described in the beacon slot 4 (BSN4). In addition, since thecommunication device 101-4 belongs to the first network group, DI=4 isassigned as the device index 502.

Since, although the beacon slot 5 (BSN5) does not receive the beacon, itis determined that the communication device 101-6 (DEVID 6) uses thebeacon slot 6 (BSN6) from the BPOIE indication from the communicationdevice 101-7, the parameters concerning the communication device 101-6are described in the beacon slot 5 (BSN5).

Since, although the beacon slot 6 (BSN6) does not receive the beacon, itis determined that the communication device 101-1 (DEVID 1) uses thebeacon slot 6 (BSN6) from the BPOIE indication from the communicationdevice 101-2, the parameters concerning the communication device 101-1are described in the beacon slot 6 (BSN6). In addition, since thecommunication device 101-1 belongs to the first network group, DI=3 isassigned as the device index 502.

Since the beacon slot 7 (BSN7) is assigned as the beacon slot fortransmission from the own device, the parameters including its ownaddress are described in the items for the beacon slot 7 (BSN7) in FIG.5.

Since the beacon slot 0 (BSN0) and the beacon slot 8 and subsequentslots (BSN8 and subsequent BSNs) are not used, no parameter is describedin these beacon slots.

FIG. 6 is a diagram schematically showing an example of the structure ofa memory area in the memory, in which the beacon information concerningother network groups is stored, according to an embodiment of thepresent invention.

The beacon information concerning other network groups in beacon periodsdifferent from the beacon period of the own device is stored in thememory area in the memory in FIG. 6.

The beacon information that is received is stored in the memory forevery beacon slot position 601.

The memory area in the memory includes a device index 602 indicatinginformation specific to the communication device and a beacon status 603indicating whether the beacon information is received in the beaconslot.

The beacon slot information 504 indicating the usage of the beacon slotin the beacon period, in the memory area in the memory in FIG. 5, isreplaced with MAS information 604 on other groups at the MAS positionsin a different beacon period in the memory area in the memory in FIG. 6.The memory area in the memory in FIG. 6 also includes the number of lostbeacons 605 indicating a counted number of beacons that are temporarilylost.

A device address 606 described in a header in FIG. 6, and a deviceidentifier 607 being information concerning the MAC address, a BSN 608,and control information 609, which are described in a beacon parameterin FIG. 6, are arranged as common information concerning the receivedbeacon.

Furthermore, a received IE bitmap 610 indicating which informationelement is included; a BPOIE 611 indicating the usage of the beaconperiod; and a capability 612, which is the information elementindicating the capability of the communication device 101, are arranged,if necessary, in an area (as IE parameters of the received beacon), inwhich parameters added as variable length information are stored. TheBPOIE 611 and the capability 612 show the content of the informationelement described in the received IE bitmap 610. However, the structureof the memory area in the memory is not limited to the above example.

FIGS. 5 and 6 show that the structure in which the beacon informationconcerning the network group of the own device is stored in the memoryis the same as the one in which the beacon information concerning othernetwork groups is stored in the memory.

The information concerning the communication device 101-3 (DEVIV3) isstored in the memory on the basis of the parameters, for example, in thestructure shown in FIG. 6.

The beacon information received by the communication device 101-3 isstored in the memory area in the memory as the information in adifferent beacon period.

The communication device 101-3 can receive the beacon informationconcerning the communication device 101-8 by receiving the beacon periodof the communication device 101-8 because the communication device 101-8(DEVID 8) operating in a different period is located near thecommunication device 101-3.

In other words, the information concerning the MAS position where thebeacon is received, the beacon information, the beacon parameters, etc.are sequentially stored in the memory from the first position for otherbeacon periods.

The communication device that belongs to another network group and thatcommunicates with the communication devices in the network group of theown device has DI=5 assigned as the device index 602.

Since the communication device 101 can determine the existence of thecommunication device 101-9 having another beacon period from the BPOIEindication from the communication device 101-8 (DEVID 8), theinformation concerning the communication device 101-9 may be stored inthe memory area in the memory.

FIG. 7 is a diagram schematically showing an example of a managementstructure of the communication devices by using information specific tothe communication device 101 (hereinafter referred to as device-specificinformation), according to an embodiment of the present invention.

The device-specific information is stored in the memory for collectivemanagement of all the communication devices 101 in the network group ofthe own device and, if necessary, communication devices 101 in a networkgroup having the same beacon period as that of the network group of theown device or communication devices 101 in network groups having beaconperiods different from the beacon period of the network group of the owndevice.

Even if the beacon slot position or the device address is changed, theparameters described for every device-specific information are used toidentify one communication device 101.

Parameters shown in FIG. 7 are managed on the basis of the devicespecific information. The memory area in the memory, shown in FIG. 7,includes a device index (DI) status 702, a device address 703corresponding to the device-specific information, transmission databuffering 704, an available MAS 705, a reserved MAS 706, a prioritizedcontention access (PCA) enabled MAS bitmap 707, an available rate 708, ahibernation count 709, a hibernation period 710, and other parameters,if necessary, for every device index 701. The device index 701 is anumber corresponding to the device-specific information. The DI status702 indicates the usage of the device-specific information. Thetransmission data buffering 704 indicates whether the transmission datais stored. The available MAS 705 is information concerning an availableMAS position. The reserved MAS 706 is information concerning a reservedMAS position. The PCA enabled MAS bitmap 707 is information concerningthe MAS position available for PCA communication. The available rate 708is information concerning an available physical layer (PHY) data rate.The hibernation count 709 indicates a counted value of the superframe toa time when the communication device 101 enters a hibernation mode. Thehibernation period 710 indicates the superframe period started in thehibernation mode. However, the management structure of the memory is notlimited to the above one.

FIG. 8 is a block diagram schematically showing an example of thestructure of a wireless communication device (communication device 101)according to an embodiment of the present invention.

Referring to FIG. 8, the communication device 101 includes an antenna801, a radio-frequency (RF) block (a conversion unit) 802, and amodulation-demodulation block (a PHY block; including a detection unit,a storage unit, and a management unit) 803. The antenna 801 is used fortransmitting and receiving a predetermined high-frequency radio signalthrough a wireless medium. The RF block 802 amplifies the receivedhigh-frequency signal to convert the amplified signal into a receptionsignal and amplifies a signal to be transmitted to convert the amplifiedsignal into a high-frequency signal. The modulation-demodulation block803 is a physical layer block that performs predetermined demodulationto a desired reception signal to generate an information bit andperforms modulation to the information bit to be transmitted to generatea transmission signal.

The modulation-demodulation block 803 receives a signal, such as abeacon signal, through the antenna 801 to detect a wirelesscommunication device having a different beacon period and/or to storethe beacon information resulting from the demodulation of the beaconsignal in an own-network-group beacon memory, an other-network-groupsbeacon memory, or a device management control memory using thedevice-specific information, which are memory areas in the memory 806(storage unit).

The communication device 101 also includes an access control block 804and a timing control block 805. The access control block 804 performsaccess control between the communication device 101 and peripheralcommunication devices 101 for wireless communication. The timing controlblock 805 controls timings of the access control for every predeterminedslot (MAS).

The timing control block 805 corresponds to at least one of, forexample, a scan setting unit, a management unit that modifies or updates(including new addition or deletion) the information concerning thedevice storage area, a calculation unit that calculates the timings, acomparison unit that compares the calculated timing of a reservedcommunication area with the timing of the reserved communication area ofthe own device, and a communication unit that sets the communicationarea.

The communication device 101 according to the embodiment of the presentinvention is characterized by including a memory 806 in which theown-network-group beacon memory, the other-network-groups beacon memory,the device management control memory, etc. are described. Theown-network-group beacon memory is an area where beacon parameterstransmitted from the communication devices 101 around the own device arestored in the beacon period of the network group of the own device. Theother-network-groups beacon memory is an area where beacon parameterstransmitted from the communication devices 101 around the own device arestored in a beacon period different from the beacon period of thenetwork group of the own device. The device management control memory isan area where information used for managing the peripheral communicationdevices 101 with which the own device communicates by using thedevice-specific information is stored.

The communication device 101 further includes a data buffer 807 used fortemporarily storing data that is received and data to be transmitted anda buffer management block 808 that accesses to the data buffer 807 andmanages the memory areas in the data buffer 807.

The communication device 101 is provided with a user interface 809 thatis connected to the communication device 101 through a beacon parameterlist, an access parameter list, or a predetermined bus 203 and thatperforms predetermined input and output and a central processing unit(CPU) 810 incorporating programs used for controlling the communicationdevice 101. The programs incorporated in the CPU 810 include a programused for controlling a time slot, an interface controller, and so on.

The CPU 810 may have a function of allocating a device identifier(device-specific information) unique to the communication device 101from the information described in the memory 806.

The communication device 101 is further provided with a data interface811 that is connected to the buffer management block 808 and the databuffer 807 through a predetermined bus 205, that passes data toapplication devices connected the communication device 101 at highspeed, and that conforms to a high-speed serial bus standard, such asUSB 2.0 or IEEE1394. The bus 205 is connected to the CPU 810 to causethe communication device 101 to perform a series of operations under thecontrol of the CPU 810.

FIG. 9 is a diagram schematically showing management of the peripheralcommunication devices 101, according to an embodiment of the presentinvention.

As shown in FIG. 9, a beacon period length parameter (X) indicating thecurrent setting for the beacon period, a maximum number of counteddevices (Y), and a maximum number of connected devices (Z) are set forevery communication device 101.

For example, it is assumed that the maximum number of counted devices(Y) is around 60. The beacon period length parameter (X) is set so asnot to exceed the maximum number of counted devices (Y). The maximumnumber of counted devices (Y), etc. may be changed, if necessary.

In other words, the communication devices 101 of up to the maximumnumber of counted devices (Y), having the beacon period of the networkgroup of the own device, can be included in the network.

The communication devices 101 of a number given by subtracting the valueof the current beacon period length parameter (X) from the maximumnumber of counted devices (Y), having beacon periods different from thebeacon period of the network group of the own device, can be added tothe network.

The communication devices 101 that actually perform the communicationare managed in accordance with the maximum number of connected devices(Z), and the device-specific information is allocated to thecommunication devices 101 in the network group of the own device, amongthe communication devices 101 having the beacon period of the owndevice. The communication devices 101 to which the device-specificinformation is allocated are included in the network.

It is assumed that the maximum number of connected devices (Z) is around32. The communication devices that do not require monitoring of thestate by unlimited access connections are discriminated.

The device-specific information is allocated as the parametersindependent of the beacon slot position or the device address, as shownby arrows in FIG. 9.

If the communication devices 101 in other network groups or havingdifferent beacon periods communicate with the communication devices 101in the network group of the own device, the device-specific informationis allocated to those communication devices 101. The communicationdevices 101 to which the device-specific information is allocated areincluded in the network.

If the communication devices 101 having other beacon periods communicatewith the communication devices 101 in the network group of the owndevice, as shown by a broken-line arrow in FIG. 9, the device-specificinformation may be allocated to the communication devices 101 having theother beacon periods.

FIG. 10 is a diagram showing an example of the structure in whichresults of beacon scanning in initial setup are stored, according to anembodiment of the present invention.

In this structure, all the areas in the superframe are used as thememory for storing the information in other beacon periods because thebeacon period of the own device is not determined in the initial setup,for example, immediately after the communication device 101 is turned onor immediately after the communication device 101 is reset.

Since the reference superframe period has not been set in such a case,the reception operation of the beacon scanning is started at anarbitrary time and is continued until a predetermined superframe period.

Specifically, as shown in FIG. 10, the received beacon information issequentially stored in the memory 806 from the first address (zero) ofthe storage area.

Information indicating how much offset time is necessary in thesubsequent setting of the superframe period of the own device in orderto store the beacon information from the beginning of the superframe canbe yielded by also storing the received MAS positions in the memory 806.

Information indicating how much time difference there is between thecommunication devices 101 having different beacon periods can also beyielded.

FIG. 11 is a flowchart schematically showing an operation of thecommunication device 101, according to an embodiment of the presentinvention.

Each communication device 101 performs the operation in a manner set forevery MAS at the start time of the MAS.

Referring to FIG. 11, in Step S101, the communication device 101determines whether the MAS is in the beacon period. In Step S102, thecommunication device 101 determines whether it is the timing of aboundary between the beacon slots. If the communication device 101determines in Step S101 that the MAS is in the beacon period anddetermines in Step S102 that it is the timing of a boundary between thebeacon slots, then in Step S103, the communication device 101 updatesthe beacon slot position.

If the communication device 101 determines in Step S102 that it is notthe timing of a boundary between the beacon slots, then in Step S104,the communication device 101 determines whether it is the timing of thetransmission beacon slot. If the communication device 101 determinesthat it is the timing of the transmission beacon slot, then in StepS105, the communication device 101 acquires a beacon parameter. In StepS106, the communication device 101 transmits the beacon.

If the communication device 101 determines in Step S104 that it is notthe timing of the transmission beacon slot, then in Step S107, thecommunication device 101 receives the beacon. In Step S108, thecommunication device 101 determines whether the beacon has beenreceived. If the communication device 101 determines that the beacon hasbeen received, then in Step S109, the communication device 101 acquiresa position where the beacon slot is stored. In Step S110, thecommunication device 101 stores the received beacon parameter in memoryarea (having the structure shown in FIG. 5) in the memory 806,corresponding to the position of the beacon slot.

In Step S111, the communication device 101 determines whether anotification of a data transmission request is received for the beaconparameter. If the communication device 101 determines that anotification of the data transmission request is received for the beaconparameter, then in Step S112, the communication device 101 sets thespecified MAS as the reception MAS. In Step S113, the communicationdevice 101 sets this setting as the transmission beacon parameter of theown device.

If the communication device 101 determines in Step S111 that anotification of the data transmission request is not received for thebeacon parameter, then in Step S114, the communication device 101determines whether it is the end of the beacon slot. If thecommunication device 101 determines that it is the end of the beaconslot, then in Step S115, the communication device 101 extends the beaconperiod which the communication device 101 manages for a newcommunication device 101 because there is no room for the newcommunication device 101 that enters the network group in the beaconslot.

If the communication device 101 determines in Step S108 that the beaconhas not been received, then in Step S116, the communication device 101determines whether it is the end of the beacon slot. If thecommunication device 101 determines that it is the end of the beaconslot, then in Step S117, the communication device 101 sets the memoryarea (having the structure shown in FIG. 6) in another beacon period.

If the process in the beacon slot is terminated, the communicationdevice 101 goes back to Step S101 and repeats the processing as long asthe beacon MAS exists.

If the communication device 101 determines in Step S101 that the MAS isnot in the beacon period, then in Step S118, the communication device101 determines whether the transmission data has been received from anapplication device connected to the communication device 101 through theinterface. If the communication device 101 determines that thetransmission data has been received from an application device connectedto the communication device 101 through the interface, then in StepS119, the communication device 101 determines whether a beacon has beenreceived from the destination communication device. If the communicationdevice 101 determines that a beacon has been received from thedestination communication device, then in Step S120, the communicationdevice 101 stores the data in the data buffer 807. In Step S121, thecommunication device 101 acquires a beacon parameter of the destinationcommunication device. In Step S122, the communication device 101calculates an unused MAS. In Step S123, the communication device 101sets the calculated MAS as the transmission MAS of the own device. Thenin Step S113, the communication device 101 sets the setting as thetransmission beacon parameter of the own device.

If the communication device 101 determines in Step S118 that thetransmission data has not been received, then in Step S124, thecommunication device 101 determines whether it is the transmission MASto which the data transmission from the own device is set. If thecommunication device 101 determines that it is the transmission MAS towhich the data transmission from the own device is set, then in StepS125, the communication device 101 acquires data from the data buffer807. In Step S126, the communication device 101 transmits the data.After transmitting the data, the communication device 101 proceeds toStep S129, if necessary, and receives data during the remaining time ofthe MAS. The communication device 101 may receive acknowledgement (ACK)information, if necessary, and may perform automatic retransmission (notshown).

If the communication device 101 determines in Step S124 that it is notthe transmission MAS to which the data transmission from the own deviceis set, then in Step S127, the communication device 101 determineswhether the superframe where the beacon scanning is performed is set. Ifthe communication device 101 determines that the superframe where thebeacon scanning is performed is set, then in Step S128, thecommunication device 101 determines whether it is the reception MAS towhich the data reception in the own device is set. If the communicationdevice 101 determines that it is the reception MAS to which the datareception in the own device is set, then in Step S129, the communicationdevice 101 receives the data. In Step S130, the communication device 101determines whether data for the own device has been received. If thecommunication device 101 determines that data for the own device hasbeen received, then in Step S131, the communication device 101 storesthe data in the data buffer 807. The communication device 101 maytransmit the ACK information back, if necessary (not shown).

In Step S132, the communication device 101 determines whether a beaconhas been received, instead of the data. If the communication device 101determines that a beacon has been received, than in Step S133, thecommunication device 101 stores the received beacon parameter in thememory area in the memory 806, where the current beacon list shown inFIG. 6 is stored, in another beacon period. In Step S134, thecommunication device 101 updates the memory area where informationconcerning the beacon, for example, information used for the managementstructure by using the device-specific information shown in FIG. 7, isstored.

In Step S135, the communication device 101 determines whether theprocessing of the corresponding MAS is terminated. If the communicationdevice 101 determines that the processing of the corresponding MAS isnot terminated, the communication device 101 goes back to Step S129 torepeat the reception processing.

If the communication device 101 determines in Step S135 that theprocessing of the corresponding MAS is terminated, the communicationdevice 101 goes back to S101 to process the subsequent MAS.

If the corresponding MAS is not the beacon MAS, not the datatransmission MAS, and not the data reception MAS, the communicationdevice 101 goes back to Step S101 to repeat the above processing becausethe communication device 101 is in the hibernation mode in thecorresponding MAS.

The above processing may be performed by dedicated hardware or bysoftware. If the above processing is performed by software, the programsin the software are installed in an information processing apparatus,such as a general-purpose computer or a microcomputer, to cause theinformation processing apparatus to function as the communication device101.

The above programs may be recorded in advance in a hard disk, a readonly memory (ROM), or the like, which serves as a recording medium builtin the computer.

Alternatively, the programs may be temporarily or permanently stored(recorded) in a removable recording medium, such as a flexible disk, acompact disc-read only memory (CD-ROM), a magneto-optical disc (MO), adigital versatile disk (DVD), a magnetic disk, or a semiconductormemory, in addition to the hard disk drive. Such a removable recordingmedium may be provided as package software.

The programs may be transferred from a web site to the computer throughan artificial satellite for digital satellite broadcasting by radiowaves or may be downloaded from a web site to the computer through anetwork, such as a local area network (LAN) or the Internet, by cables,in addition to the installation from the above removable recordingmedium to the computer. The computer receives the programs transferredin the above manner and installs the received programs in the hard diskbuilt therein.

The steps describing the programs causing the computer to perform avariety of processing are not necessarily processed in time series inthe order described in the flowchart in this specification. The stepsmay be performed in parallel or individually (for example, including aparallel process or an object process).

The wireless communication device according to the embodiment of thepresent invention has the following features.

Providing the area where the beacon information concerning the networkgroup of the own device is stored and also providing the area where thebeacon information concerning other network groups is stored allow thecommunication device 101 to manage the multiple network groups near thecommunication device 101.

The communication device 101 can efficiently collect the informationfrom the communication devices in other network groups, around thecommunication device 101, by causing the area where the beaconinformation concerning other network groups is stored to have the samestructure as that of the area where the beacon information concerningthe network group of the own device is stored. Accordingly, it ispossible to easily manage the ad hoc network by the autonomousdistributed control.

Determining the maximum number of counted communication devicessupported by the own device and sequentially storing the beaconinformation concerning the communication devices having different beaconperiods from the end of the area where the beacon information in thebeacon period of the own device is stored allow the communication device101 to effectively use the limited memory space.

It is possible for the communication device 101 to efficiently collectthe beacon information resulting from the initial scanning operation andthe normal beacon information from the communication devices 101 in thenetwork group of the own device.

Performing the scanning operation in a predetermined beacon period, inaddition to the initial scanning operation, allows the communicationdevice 101 to easily detect the presence of the networks or thecommunication devices having different beacon periods.

Collecting the beacon information concerning the communication devices101 in different network groups, acquiring information concerning thecommunication areas used by the communication devices 101, and comparingthe acquired communication areas with the communication area used by theown device allow the communication device 101 to change the settingssuch that the timings of the communication areas do not coincide witheach other.

Collecting the beacon information concerning the communication devices101 in different network groups, acquiring information concerning thecommunication areas used by the communication devices 101, andsuppressing the transmission of the data from the own device at thetimings included in the acquired information can provide an effectivemethod of allowing the coexistence of the different networks.

Performing the management by using the device-specific informationspecific to the communication devices 101 allows the communicationdevice 101 to use the parameters relating to the access control and thebuffered data, without excluding such data, even if the beacontransmission position of a certain communication device is changed.

Individually providing the device-specific information having a lengthof about two bytes to manage each communication device 101 eliminatesthe need to use redundant information, such as the MAC addresses (eightbytes), for the management to identify the communication device 101,even if the identifier of the communication device 101 in the network ischanged.

The use of the device-specific information allows simple determinationof the destination communication device 101 that receives the data.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. A wireless communication device included in a first network group andhaving a first beacon period, the wireless communication devicecomprising: scanning setup means for scanning at arbitrary timings, inaddition to an initial scanning; detecting means for detecting a secondwireless communication device included in a second network group thatdoes not include the wireless communication device and having a secondbeacon period different from the first beacon period; memory means forstoring beacon information corresponding to the second wirelesscommunication device in a memory area, wherein the beacon information isstored in a first format and includes a header and a plurality ofcategorized sections for storing different types of data correspondingto the second beacon period; calculating means for calculating a timingat which a reserved communication area of the second wirelesscommunication device is set from at least the beacon information storedin the memory means; comparing means for comparing the timing of thecalculated reserved communication area with the timing of a reservedcommunication area of the wireless communication device; and settingmeans for setting the communication area of the wireless communicationdevice such that the timing of the communication area of the wirelesscommunication device does not coincide with the timing of thecommunication area of the second wireless communication device, inaccordance with the comparison result.
 2. The wireless communicationdevice according to claim 1, wherein the memory means further storesbeacon information corresponding to the wireless communication device,the beacon information corresponding to the wireless communicationdevice being arranged in the first format.
 3. The wireless communicationdevice according to claim 1, wherein the memory means further storesbeacon information resulting from the initial scanning, the beaconinformation resulting from the initial scanning being arranged in afirst format, and the memory means stores beacon informationcorresponding to the wireless communication device, the beaconinformation corresponding to the wireless communication device beingarranged in the first format.
 4. The wireless communication deviceaccording to claim 2, further comprising setting means for setting amaximum number of counted communication devices in the first network andthe second network, wherein the memory means sequentially stores thebeacon information corresponding to the second wireless communicationdevice and the beacon information corresponding to the wirelesscommunication device.
 5. The wireless communication device according toclaim 1, further comprising: allocating means for allocating a deviceidentifier specific to each of a plurality of wireless communicationdevices around the wireless communication device; and managing means formanaging the plurality of wireless communication devices, which aredestination devices, by using the device identifier.
 6. A wirelesscommunication method for a wireless communication device included in afirst network group having a first beacon period, the method comprising:scanning at arbitrary timings, in addition to an initial scanning;detecting a second wireless communication device included in a secondnetwork group that does not include the wireless communication deviceand having a second beacon period different from the first beaconperiod; storing beacon information corresponding to the second wirelesscommunication device in a memory area, wherein the beacon information isstored in a first format and includes a header and a plurality ofcategorized sections for storing different types of data correspondingto the second beacon period; calculating a timing at which a reservedcommunication area of the second wireless communication device is setfrom at least the stored beacon information; comparing the timing of thecalculated reserved communication area with the timing of a reservedcommunication area of the wireless communication device; and setting thecommunication area of the wireless communication device such that thetiming of the communication area of the wireless communication devicedoes not coincide with the timing of the communication area of thesecond wireless communication device, in accordance with the comparisonresult.
 7. A non-transitory computer-readable medium storinginstructions, which, when executed by a processor of a wirelesscommunication device included in a first network group having a firstbeacon period, causes the processor to perform a method comprising:scanning at arbitrary timings, in addition to an initial scanning;detecting a second wireless communication device included in a secondnetwork group that does not include the wireless communication deviceand having a second beacon period different from the first beaconperiod; storing beacon information corresponding to the second wirelesscommunication device in a memory area, wherein the beacon information isstored in a first format and includes a header and a plurality ofcategorized sections for storing different types of data correspondingto the second beacon period; calculating a timing at which a reservedcommunication area of the second wireless communication device is setfrom at least the stored beacon information; comparing the timing of thecalculated reserved communication area with the timing of a reservedcommunication area of the wireless communication device; and setting thecommunication area of the wireless communication device such that thetiming of the communication area of the wireless communication devicedoes not coincide with the timing of the communication area of thesecond wireless communication device, in accordance with the comparisonresult.
 8. A wireless communication device included in a first networkgroup and having a first beacon period, the wireless communicationdevice comprising: a scanning setup unit configured to scan at arbitrarytimings, in addition to an initial scanning; a detection unit configuredto detect a second wireless communication device included in a secondnetwork group that does not include the wireless communication deviceand having a second different beacon period different from the firstbeacon period; a memory unit configured to store beacon informationcorresponding to the second wireless communication device in a memoryarea, wherein the beacon information is stored in a first format andincludes a header and a plurality of categorized sections for storingdifferent types of data corresponding to the second beacon period;calculating unit for calculating a timing at which a reservedcommunication area of the second wireless communication device is setfrom at least the beacon information stored in the memory means;comparing unit for comparing the timing of the calculated reservedcommunication area with the timing of a reserved communication area ofthe wireless communication device; and setting unit for setting thecommunication area of the wireless communication device such that thetiming of the communication area of the wireless communication devicedoes not coincide with the timing of the communication area of thesecond wireless communication device, in accordance with the comparisonresult.